The invention relates to marine propulsion devices, and, more particularly, to the assembly of marine propulsion devices. Still more particularly, the invention relates to methods and apparatus for determining the necessary shim thickness for a marine propulsion device pinion and bearing carrier assembly.
A known marine propulsion device, and more particularly a known stern drive unit, includes a generally vertical drive shaft having a pinion or bevel gear splined or otherwise connected to its upper end. The pinion has a generally planar end surface and is supported by bearings that are in turn supported by a bearing carrier. The bearing carrier is in turn supported by the upper gearcase or housing of the stern drive unit. More particularly, the upper gearcase has therein an annular, generally horizontal, generally planar surface, and the bearing carrier has thereon an annular, generally planar surface spaced from the wall surface by a shim or shims. The pinion end surface must be located a relatively precise distance from the housing wall surface so that the pinion properly meshes with another pinion that is also supported by the housing and that is driven by the engine. The distance between the pinion end surface and the housing wall surface is varied by varying the thickness of the shims between the bearing carrier surface and the housing wall surface.
In the past, the necessary shim thickness has been determined by measuring the distance between the bearing carrier surface and the pinion end surface on a given pinion and bearing carrier assembly and then subtracting the measured distance from the desired distance between the pinion end surface and the housing wall surface. The distance between the pinion end surface and the bearing carrier surface has been measured with a conventional device capable of measuring the distance between two parallel surfaces.